How was SnapChat able to grow so quickly?

I'm answering your question assuming that you hope to be able to replicate it's own success in your own mobile app.

There are a couple of factors responsible for it's growth that are instructive to anyone building a mobile app.

"Leveraging the intimacy and privacy of the mobile phone."
We now have an *intimate* relationship with our phone like no other device in the history of technology. Every internet company that started before around 2010 has built their core interactions around "the old web" one which was accessed primarily via a browser on a computer.

Companies that start with a clean slate, should be building their interactions around how to do whatever the app is supposed to do while leveraging what is unique to people's relationship to their mobile devices. Photo-sharing has become a core part of the way we communicate now. Snapchat built something that provided an experience that leveraged the feeling of privacy and intimacy that is unique to mobile.

"Provided an escape from the "maturity" of other online services." Too many parents, aunts, uncles and other "old people" have encroached into the social networks of teens and young people. As a result, they've had a desire to find places to express themselves in places inaccessible by older generations. An important distinction is that it's not just parents and relatives that young people are trying to avoid, but also employers & colleges who are increasingly using "mature" social networks to review applicants.

"Leveraged PR even bad PR" The fact that the app got so much press about it being used to sext was perfect PR for the company, as it essentially reinforced the brand experience that it has today. Essentially, "if it's safe enough to send a sext, it's safe for any kind of communication I want to have." And although the safety and security of Snapchat is actually not as advertised, it still enjoys the reputation of having less impact than any primarily web-based service.

Building a successful mobile application is one of the hardest challenges to face designers, programmers and entrepreneurs in the history of writing software. Happy to talk to you if you're considering building a mobile app, about what I've learned about the "table stakes" for success.

It's a pretty long answer. My colleague recently published a several page analysis of Snapchat's growth (link below). But a quick summary is that Snapchat is almost the perfect product for driving natural word of mouth and engagement. It was released by Stanford students for the iPhone, but didn't really grow quickly until it was discovered by high school students. Growth was amplified by the Android release and international expansion.

There are several reasons SnapChat was able to grow so quickly. Here's my take on the biggest factors.

1. Network Effects/Communication apps - the most viral products are those that have increasing value as more friends use them. Typical examples include FB, LinkedIn but even more extreme as pure viral products are communication tools such as a phone, text message or email, which effectively have zero value without at least 1 other person using them. Products such as these face a huge challenge of making something addictive enough that it will be used at high frequency between friends but if they're able to achieve this they can generate almost indefensible network effects.

2. Reduced friction - photo-sharing is one of the most frequent daily behaviors of smart phone users. By making photos private and disappearing Snapchat reduced the friction or hesitation to share since: a) you're more likely to share a goofy photo and send more per day if it's not on FB and b) you're more likely to send something a little edgy (whatever that means to you) if it's going to disappear. In addition the UI is one screen which makes it extremely easy and fast to send a photo or video in the moment

3) Stickiness - snapchat's disappearing photo feature makes each incoming snap a surprise. There are several games that have leveraged this technique for years to get users to come back but the brilliance of snapchat is that it's baked into the product itself

4) Fun - by building a product that takes several features users are already doing but packaging them together SnapChat has created a fun, addicting and unique brand. Being able to send a photo, draw on it and add text make it more addicting.

5) Mobile & app rankings - it's hard to get noticed or build a growth strategy around a mobile only product. The best chance of doing so is to build a great product that leverages word of mouth, has great design, low activation barriers (simple) and some form of virality built in (easy way to invite phone contacts or syndicate to social networks). Once you do however reach a wide enough audience, appearing at the top of the charts in app rankings adds additional fuel to your mobile growth.

For the past several years companies have leveraged FB as the most effective viral strategy but I believe we are seeing a shift towards your mobile phone & contacts as being the biggest untapped distribution platform and one that FB cannot control or police

1. It solves a problem for the heaviest mobile using demographic (sexting, snooping parents, etc)
2. Its social, social apps that are engaging have the potential for exponential growth
3. Media exposure via controversy and bloggers
4. Solid user experience
5. They had technical co-founder (this is a big one) this help them get to a point of viability
6. Funding, they had access to money when it was needed
7. Luck, there is always a certain level of randomness, I guarantee that you could create an app that follows all the same steps as SnapChat and go completely unnoticed

The under 25 age group LOVES it because their parents do not know what it is and can not helicopter over their online accounts- like in FB, twitter or Instagram .
The kids THINK it's private. That the snaps go away.
It is something the kids have that is completely their own. Few people over 26 even use snapchat.
They can pretty much control who does or does not see their snaps.
Most adults can't wrap their heads around it because the kids just snap completely sophomoric and ridiculously childish stuff that adults don't get the appeal of.
When the grow ups start infiltrating snap chat the kids will leave and it will morph into an advertising and sales business machine like facebook, twitter and Instagram have become.

Crazy stuff always works among social groups. Snapchat became instant hit because of the following factors:

1. It is easy to take a pic and share in comparison to write text
2. It has cool image filters
3. Experiment with the pics
4. Dedicated for sharing pics, that made it special.
5. Social networks grow viral due to multiplier social effect